Alan King wrote:
> Anyone up for making a serial device?  I only do a little programming
> on the PC side of things, so am not currently up to the task I
> think. Needs sync bytes, something like this is common:
>
> FF FF 0 axis1 0 axis2 0 axis3 etc.

RS232 is an async protocol, there's no need for any synchronization in
the application (that's what the "start bit" is for).  Just send the
data you want and it will come out the other side.  If you saw an
application doing this in the past, it's probably one that was trying
to do "autobaud" detection, which is a rats nest you don't need to
worry about for custom hardware.  Or maybe it was transmitting to
broken hardware that wasn't fast enough to handle real RS232.

You might want to put a "magic number" at the top of a packet to
handle dropped bytes gracefully, but that's a slightly different
problem.  You certainly don't want to embed padding bytes in the
message itself.

Andy



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